Sensitivity of dairy calf Salmonella enterica serotype Cerro isolates to infection-relevant stressors.

Salmonella enterica serotype Cerro (S. Cerro) is an emerging Salmonella serotype isolated from cattle, but the association of S. Cerro with disease is not well understood. While comparative genomic analyses of bovine S. Cerro isolates have indicated mutations in elements associated with virulence, the correlation of S. Cerro fecal shedding with clinical disease in cattle varies between epidemiologic studies. The primary objective of this study was to characterize the infection-relevant phenotypes of S. Cerro fecal isolates obtained from neonatal calves born on a dairy farm in Wisconsin, USA. The S. Cerro isolates varied in biofilm production and sensitivity to the bile salt deoxycholate. All S. Cerro isolates were sensitive to sodium hypochlorite, hydrogen peroxide, and acidic shock. However, S. Cerro isolates were resistant to nitric oxide stress. Two S. Cerro isolates were unable to compete with S. Typhimurium during infection of calf ligated intestinal loops, indicating decreased fitness in vivo. Together, our data suggest that S. Cerro is sensitive to some innate antimicrobial defenses present in the gut, many of which are also used to control Salmonella in the environment. The observed phenotypic variation in S. Cerro isolates from a single farm suggest phenotypic plasticity that could impact infectious potential, transmission, and persistence on a farm.IMPORTANCESalmonella enterica is a zoonotic pathogen that threatens both human and animal health. Salmonella enterica serotype Cerro is being isolated from cattle at increasing frequency over the past two decades; however, its association with clinical disease is unclear. The goal of this study was to characterize infection-relevant phenotypes of S. Cerro isolates obtained from dairy calves from a single farm. Our work shows that there can be variation among temporally related S. Cerro isolates and that these isolates are sensitive to killing by toxic compounds of the innate immune system and those used for environmental control of Salmonella. This work contributes to our understanding of the pathogenic potential of the emerging pathogen S. Cerro.

Prognostic indicators for survival of downer cattle treated using a flotation tank in a referral hospital: 190 cases (2000-2020).

BACKGROUND: Nonambulatory cattle present therapeutic challenges in addition to animal welfare concerns. Flotation therapy is a treatment option, but more information regarding prognostic indicators for survival is needed to guide use of this modality. HYPOTHESIS/OBJECTIVES: Evaluate historical and clinical variables assessed during hospitalization as prognostic indicators for survival in recumbent cattle undergoing flotation treatment in a referral hospital. ANIMALS: A total of 190 nonambulatory dairy cattle. METHODS: Retrospective case series. Medical records were analyzed from cattle undergoing flotation between 2000 and 2020. Univariable and multivariable logistic regression analyses were performed to assess the association of clinical variables with survival to discharge. RESULTS: Eighty-nine of 190 (47%) recumbent cattle survived to discharge. For each additional day of hospitalization, cattle were 1.10 (95% confidence interval [CI], 1.02, 1.21) times more likely to survive. Cattle unable to walk out of the tank after their first float session were 0.11 (95% CI, 0.04, 0.28) times less likely to survive compared to cattle that could and inappetent cattle were 0.22 (95% CI, 0.07, 0.63) times less likely to survive compared to cattle with normal appetites. Cattle diagnosed with coxofemoral luxation or toxemia were 0.11 (95% CI, 0.02, 0.65) and 0.16 (95% CI, 0.02, 0.90) times less likely to survive, respectively, compared to cattle with causes of recumbency that were undetermined. CONCLUSIONS AND CLINICAL IMPORTANCE: Walking out of the tank after the first float session, appetite, diagnosis, and days of hospitalization are associated with outcome in nonambulatory dairy cattle treated by flotation. These findings can be used to determine likely outcome and guide treatment, referral, or euthanasia decisions.

Assessing the effects of experimental bacterial challenge with Pasteurella multocida and ampicillin on the respiratory microbiota of pre-weaned Holstein calves.

The association between changes in the respiratory microbiota and Bovine Respiratory Disease (BRD) in dairy calves is not well understood. We investigated characteristics of the nasopharyngeal (NP) microbiota associated with BRD following Pasteurella multocida infection. We also evaluated the effect of ampicillin on the respiratory microbiota. Calves (n = 30) were inoculated with P. multocida and randomly allocated into an antibiotic group (AMP; n = 17) or placebo group (PLAC; n = 11) when lung lesions developed. Deep NP swabs (DNPS) were collected before and after challenge. Monitoring was performed daily until euthanasia at day 14. Swabs and tissue samples were collected for analysis. The V4 hypervariable region of the 16 S rRNA gene was amplified and sequenced on an Illumina MiSeq. Increased species abundance in the pre-challenge DNPS was associated with a decrease in cumulative respiratory disease over 14 days post-infection. While NP beta diversity was affected by infection, antibiotic therapy showed no effect on the alpha and beta diversity nor the relative abundance (RA) of genera in the NP tonsil, lymph node and lung microbiota. Antibiotic therapy was associated with an increased RA of NP Pasteurella spp. and a decreased RA of NP Prevotella spp. Common taxa among all samples included GIT-associated bacteria, which suggests a possible link between the GIT microbiota and respiratory microbiota in dairy calves.

Changes in the host transcriptome and microbial metatranscriptome of the ileum of dairy calves subjected to artificial dosing of exogenous rumen contents.

Development of a properly functioning gastrointestinal tract (GIT) at an early age is critical for the wellbeing and lifetime productivity of dairy cattle. The role of early microbial colonization on GIT development in neonatal cattle and the associated molecular changes remain largely unknown, particularly for the small intestine. In this study, we performed artificial dosing of exogenous rumen fluid during the early life of the calf, starting at birth through the weaning transition at 8 wk. Six calves were included in this study. At 8 wk of age, tissue from the ileum was collected and subjected to host transcriptome and microbial metatranscriptome analysis using RNA sequencing. A total of 333 genes showed significant differential expression (DE) (fold-change ≥2; adjusted P < 0.1, mean read-count ≥10) between the treated and control calves. Gene ontology analysis indicated that these DE genes are predominantly associated with processes related to the host immune response (P < 0.0001). Association analysis between the host gene expression and the microbial genus abundance identified 57 genes as having significant correlation with the ileum microbial genera (P < 0.0001). Of these, three genes showed significant association with six microbial genera: lysozyme 2 (LYZ2), fatty acid binding protein 5 (FABP5), and fucosyltransferase (FUT1). Specifically, the profound increase in expression of LYZ2 in treated calves suggests the initiation of antibacterial activity and innate response from the host. Despite the limitation of a relatively small sample size, this study sheds light on the potential impact of early introduction of microbes on the small intestine of calves.

The effect of foot-and-mouth disease vaccination on early pregnancy loss in beef heifers in Argentina.

The threat of Foot and Mouth Disease (FMD) in South America has global economic implications and retaining a FMD Free status under the World Organization for Animal Health (OIE) remains a top priority. In Argentina the Servicio Nacional de Sanidad y Calidad Agroalimentaria (SENASA), the national service of agri-food health and quality, requires cattle located in the Pampean region of the Salado River basin to receive two foot-and-mouth disease (FMD) vaccinations per year, which results in one vaccination coinciding with beef cattle breeding season. While the vaccination program remains necessary, there is a growing concern amongst food animal veterinarians, that the overlap of FMD vaccination with the first 35 days of the breeding season is associated with early pregnancy loss (EPL). To address this concern, a preliminary randomized controlled trial t study was conducted to investigate the risk ratio (RR) of EPL in vaccinated, pregnant Aberdeen Angus heifers. Initially (Day 0), 858 heifers underwent fixed time-AI (FTAI). Subsequently, on day 33, following pregnancy diagnosis by transrectal ultrasonography pregnant heifers (n = 311) were randomly allocated to two treatment groups. Group 1 (162 animals) received an inactivated oil emulsion FMD vaccine, and Group 2 (149 animals) received a saline injection (control). On day 51 (18 days post vaccination), pregnancy status was re-evaluated by ultrasonography. The initial pregnancy rate (PR) on Day 33 was 58% (498/858 animals). On Day 51 (18 days post vaccination), PR in Group 1 was 96.3% (156/162 animals), and in Group 2 (control) was 98.6% (147/149 animals). The EPL in Group 1 was 3.7% (6/162 animals) and in Group 2 was 1.3% (2/149 animals). The RR of EPL in Group 1, compared to Group 2, was 2.8 (95% confidence interval: 0.6-13, p-value: 0.20). With such a wide range in confidence intervals and a p value of 0.20 a larger prospective study would be necessary to establish an unequivocally statistically significant link between heifer vaccination 33 days post FTAI and an increased risk of EPL.

Author Correction: Transcriptomics analysis of host liver and meta-transcriptome analysis of rumen epimural microbial community in young calves treated with artificial dosing of rumen content from adult donor cow.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.

Effects and immune responses of probiotic treatment in ruminants.

Gut microbial colonization and establishment are vital to ruminant health and production. This review article focuses on current knowledge and methods used to understand and manipulate the gut microbial community in ruminant animals, with a special focus on probiotics treatment. This review highlights the most promising of studies in this area, including gut microbial colonization and establishment, effect of gastrointestinal tract microbial community on host mucosal innate immune function, impact of feeding strategies on gut microbial community, current probiotic treatments in ruminants, methods to manipulate the gut microbiota and associated antimicrobial compounds, and models and cell lines used in understanding the host immune response to probiotic treatments. As a lot of work in this area was done in humans and mice, this review article also includes up-to-date knowledge from relevant studies in human and mouse models. This review is a useful resource for scientists working in the areas of ruminant nutrition and health, and to researchers investigating the microbial ecology and its relation to animal health.

Transcriptomics analysis of host liver and meta-transcriptome analysis of rumen epimural microbial community in young calves treated with artificial dosing of rumen content from adult donor cow.

In mammals, microbial colonization of the digestive tract (GIT) occurs right after birth by several bacterial phyla. Numerous human and mouse studies have reported the importance of early gut microbial inhabitants on host health. However, few attempts have been undertaken to directly interrogate the role of early gut/rumen microbial colonization on GIT development or host health in neonatal ruminants through artificial manipulation of the rumen microbiome. Thus, the molecular changes associated with bacterial colonization are largely unknown in cattle. In this study, we dosed young calves with exogenous rumen fluid obtained from an adult donor cow, starting at birth, and repeated every other week until six weeks of age. Eight Holstein bull calves were included in this study and were separated into two groups of four: the first group was treated with rumen content freshly extracted from an adult cow, and the second group was treated with sterilized rumen content. Using whole-transcriptome RNA-sequencing, we investigated the transcriptional changes in the host liver, which is a major metabolic organ and vital to the calf's growth performance. Additionally, the comparison of rumen epimural microbial communities between the treatment groups was performed using the rRNA reads generated by sequencing. Liver transcriptome changes were enriched with genes involved in cell signaling and protein phosphorylation. Specifically, up-regulation of SGPL1 suggests a potential increase in the metabolism of sphingolipids, an essential molecular signal for bacterial survival in digestive tracts. Notably, eight genera, belonging to four phyla, had significant increases in abundance in treated calves. Our study provides insight into host liver transcriptome changes associated with early colonization of the microbial communities in neonatal calves. Such knowledge provides a foundation for future probiotics-based research in microbial organism mediated rumen development and nutrition in ruminants.

Identification by next-generation sequencing of Aichivirus B in a calf with enterocolitis and neurologic signs.

An 11-d-old Holstein bull calf was presented to the Veterinary Medical Teaching Hospital at the University of Wisconsin-Madison because of a 4-d history of diarrhea and persistent low-grade fever. Initial diagnosis was enteritis caused by Cryptosporidium and rotavirus. During hospitalization, the calf became stuporous and was only responsive to noxious stimuli, with hypotonia of all 4 limbs, tail, head, and neck. A cerebrospinal fluid analysis revealed xanthochromia, with marked lymphocytic pleocytosis, which was suggestive of viral meningitis and/or encephalitis. Aichivirus B, which belongs to the Kobuvirus genus, was tentatively identified in spinal fluid by next-generation DNA sequencing. This virus can affect a multitude of species, including humans and cattle, and has been isolated from both healthy and diarrheic individuals. However, to date, a possible connection with neurologic disease has not been described, to our knowledge.

Epizootic hemorrhagic disease in a yak.

Epizootic hemorrhagic disease virus (EHDV) infection was diagnosed in a 3-year-old yak. The yak had signs of intermittent tremors, dysphagia, oral ulcerative lesions, hemorrhagic enteritis, tachypnea, and thrombocytopenia. Postmortem diagnostics confirmed EHDV (serotype 2) using reverse-transcriptase polymerase chain reaction (RT-PCR). Gross and histopathological results were consistent with EHDV reported in other species.

Épizootie hémorragique chez un yack. Une infection par le virus de la maladie épizootique hémorragique du cerf a été diagnostiquée chez un yack âgé de 3 ans. Le yack présentait des signes de tremblements intermittents, de dysphagie, de lésions ulcératives buccales, d'entérite hémorragique, de tachypnée et de thrombocytopénie. Le diagnostic postmortem a confirmé l'épizootie hémorragique (sérotype 2) à l'aide de la technique RT-PC. Les résultats bruts et histopathologiques étaient conformes à l'épizootie hémorragique signalée chez d'autres espèces.(Traduit par Isabelle Vallières).